Strut platform support



p .1953 L. s. WILLIAMS 2,652,241

STRUT PLATFORM SUPPORT Filed Jan. 5, 1951 s Sheets- Sheet 1 Zhwentor 'law'rence 6. VV/W/b/ns Sept. 15, 1953 L. s. WILLIAMS STRUT PLATFORM SUPPORT 2,652,241, Filed Jan. 6, 1951 3 Sheets-Sheet 2 Zhmentor Low/"enc S. W/7//'oms 85 Gatorncg:

Sept. 15, 1953 L. s. WILLIAMS 2,652,241

STRUT PLATFORM SUPPORT Filed Jan. 6, 1951.

s Sheets-Sheet a Snventor Patented Sept. 15, 1953 STRUT PEATFORM' SUPPORT Lawrence S. Williams, Toledo, Qhio assignor to- Toledo Scale. Company, Toledo, Ohio, at corporation. of New Jersey Application January 6, 1951 5 Claims.

This invention relates to weighing. scales and in particular to supporting structure for carryinga load receiver'or platform. on a plurality of hydrauliccapsules.

One of the difiiculties that must beovercome in the construction ot any hydraulic weighing; scale is the weakness of the capsules in resisting hori zontally applied rces. Suchiorcesmay result from the starting or stopping: of trucks or other vehicles being driven across the load receiver. The permissible: lateral movement of the pressure tip the capsule pressure plate with: respect tdits base, In: this connection it-is also: desirable that-the point of force application to the capsule should: be. as close. as: possible tothe hydraulic chamber or the capsule to reduce the moment arm of any horizontal forces applied to the capsule.

The principal object ofthis; invention-is. to; pro.- vide a load receiver supporting structure that is mounted on a capsule and that serves to centralize theappli'cation of force to the" capsule and only suflicient lateral and capsule to. insure that the receiver returns to its central position when the lateral forces are 'nolonger applied;

Another object of the invention is to provide an extremely compact supporting: system. offering little resistance to horizontal movement of the loadreceiver'.

A still further object of the invention is to provide aing to center the platform is exerted when the platform is laterally displaced by horizontally applied forces.

A still further object oi'the inventionxis'. to provide a collar of rubber or other resilient material that-is compressed between a pair of shallow sockets one mounted on the strut and the other on the load receiver, said collar serving to protect e hafiiiiiedsurfaces and providing some-restoring force in addition to that of the strut.

More specific objects and advantages are ap- Serial'No. 204;789-

parent. from the following description. of preferred embodiments of the invention.

According; to: the invention the load receiver of ahydr'au lic subjecteditoload.

Figure IV is a diagrammatic sketch showing. the relationship between. the. length of the strut and the radii; of. curvature; of the. various cooperating. surfaces Figure V is a. fragmentary vertical section of a modified; formof strutas'sembly.

Figure; VI is a diagrammaticillustration. showanother arrangement: constructed according to the invention.

Figure: VIII is a diagrammatic sketch. to show the: radius. of curvature of the cooperating surfaces of the elementsc'sliown inFigure VII.

Figures IX and. .21 show still another possible arrangement of the sel tstaloi'lizing strut.

Figure XI' is a horizontal. section taken along the: line: Figure- IX.

Figure mxis-ian-t-isometric. viewer the resilient collar that isinterposed. between. the members at theupperend: ofithe-strut.

These: specific figures and the: accompanying description are: intended merely: to. illustrate the invention and not tol-im-it its scope.

In a hydraulic weighing scale constructed according to the invention: a: load receiver comprising. a. girder or beam l is supported by a strut assembly 2 from a hydraulic capsule 3. The capsule 3 includes a base member 4 that is supported from a pier or foundation 5 by a corrugated lead sheet 6 interposed between the base member 4 and the foundation 5. The corrugated lead cushion or sheet 6 yields with the initial application of load to the load receiver and by such yielding allows the base member 4 of capsule to be uniformly supported throughout its area. A capsule plate 1 that includes a clamping ring 8 is hydraulically supported from the base member 4 by hydraulic fluid confined within a rubber liner comprising an upper membrane 9 and a lower membrane Ill. The rubber membranes 9 and H) are held in fluid tight engagement with each other around the periphery of the capsule by a plurality of bolts drawing the clamping ring 8 tightly against the upper capsule plate 1. In the gap between the periphery of the base member 4 and the clamping ring 8 the membrane I is supported by a plurality of narrow metallic strips l2 which, while being flexible in bending, are non-stretchable and thus prevent stretching of the membrane ID in the gap. A coupling I3 is provided to hydraulically connect a pressure pipe l4 through a neck l5 and to the hydraulic space within the capsule 3.

A plurality of threaded studs l6 erected from the upper capsule plate 1 adjustably support a pair of horizontal arms |1 connected to a pipe Hi. The pipe I8 is part of a frame work that connects the capsule plate 1 to the capsule plates of the remaining capsules. The frame work, by interconnecting the plates, prevents tipping of the capsule pressure plates with respect to the base members 4.

Each corner of the load receiver is supported on a strut assembly comprising a strut assembly foot l9 that is centrally positioned on the pressure plate 1 and that has a vertical generally cylindrical section which is internally threaded to receive an externally threaded socket 20. A strut bearing 2| fitted in the bottom of a bore in the socket supports the lower end of a strut 22. The upper end of the strut 22 supports a top plate 23 attached to the bottom surface of the load receiver girder A collar 24 that is fixedly mounted on the strut 22 has a socket 25 in its upper surface in juxtaposition to a socket 26 in the top plate 23. A molded rubber collar 21 that fits p into the sockets and around the strut 22 serves to position the strut 22 with respect to the top plate 23 and at the same time exert a restoring force when the receiver is deflected laterally.

To accommodate lateral movement of the load receiver the greater portion of the hole in the socket 20 is tapered. This taper is sufficient to accommodate any lateral movement that is permitted by platform stops or bumpers that are ordinarily installed in the walls of the pit in which the load receiver is installed. The bottom end of the hole in the socket 20 is cylindrical to closely fit the strut bearing 2|. The cylindrical portion of the hole extends upwardly beyond the strut bearing 2| and half way past a groove 28 encircling the bottom end of the strut. The strut itself is also a close fit within the cylindrical bore of the hole in the socket 20. To accommodate lateral movement the upper surface of the strut bearing 2| is formed as a section of a spherical surface. The cooperating lower end surface of the strut 22 is flat. Likewise the upper end of the strut 22 is formed as a section of spherical surface and the cooperating surface of the top plate 23 is flat. These members are constructed of a material that can be hardened sufficiently to withstand, without permanent yield, the high forces that are transmitted through the comparatively small area of contact between the members. Thus the force from the load on the load receiver is transmitted downward from the flat undersurface of the top plate 23 to the upper end of the strut 22 and from the fiat bottom of the strut 22 to the spherical surface of the strut bearing 2| that is supported directly from the pressure plate 1 of the capsule 3.

The relative position of the various parts of the strut 22 and top plate 23 in their no-load condition is shown in Figures II and III. The rubber or resilient member 21 is of such thickness that the upper end of the strut 22 is separated a small distance from the top plate 23. When load is applied, for example the weight of the load receiver, the resilient member is compressed until the strut 22 contacts the top plate 23. This application of a preload to the resilient member 21 increases its capacity to withstand and resist angular movement of the strut 22 with respect to the top plate 23.

One of the objects of the invention is to support the load receiver in a stable condition and at the same time allow it to move laterally without transmitting large lateral forces to the supporting capsules. To satisfy this condition the ends of the strut and the cooperating surfaces of the strut bearing 2| and the top plate 23 must have particular degrees of curvature. It is possible by varying the curvature to make the system exhibit either stable equilibrium, neutral equilibrium or unstable equilibrium. The condition which exists depends upon the radii of curvature of the surfaces and the length of the strut. Figure 1V illustrates in schematic form the condition required for neutral equilibrium in the preferred form. In this figure the bottom end of the strut 22 and the lower surface of the top plate 23 are each flat, 1. e., each has an in- The strut bearing 2| has as small a radius of curvature as can be made without concentrating the load over such a small area that permanent yield of the strut or bearing material occurs. In a medium size truck scale the diameter of the strut bearing 2| and the radius of curvature of its upper surface are equal and each is one inch in length. The upper end of the strut 22 is also curved with a radius of curvature'R of a length such that the sum of the radius of curvature of the strut bearing 2| plus the radius of curvature of the upper end of the strut 22 is equal to the length L-' of the strut 22. It may be shown that under this condition, at least for small lateral movements, the load receiver moves in a horizontal direction and is therefore in neutral equilibrium. If the radii of curvature are decreased so that the sum is less than the length of the strut the system is unstable and any lateral deflection produces a force tending to increase the deflection. Likewise, if the sum of radii of curvature is greater than the length of the strut the resulting system is in a condition of stable equilibrium and is urged toward its midposition by force that is proportional to the lateral displacement of the load receiver and load on the load receiver of the scale. In the preferred form of the invention the radii of curvature are selected for substantially neutral equilibrium and the resilient collar 21 supplies the restoring force.

Figure V showsa similar strut construction upper end of the strut is R1, and the radiusof curvature at the bottom endof the strut, is R2. The; radius of curvature Of the top plate 2321' is Re and the radius of curvature of the strut bearstru t and the other of which involves the radius of curvature of the two contacting surfaces at the; top of the strut. Each of these functions isthe product of the radii of curvaturedivided by the sum of the radii of curvature. function representing the equivalent radii of curvature at the bottom end of the strut 22a is:

R2R4 eq R2=F-R4 In this example, as in the precedingeiiample, if the; radius of curvature of any of the surfaces is increased beyondthat giving neutral equilibrium thesystem becomes stable while if the radius is decreased the system becomes unstable. In fact the preferred embodiment is a specialcase wherein R2 and R of the Figure VI are infinite in length, i. e., bottom surfaces of the strut 22a and of the top plate 23a are flat. In this case the specified functions (the sum of which for neutral equilibrium is equal to the length of the strut) reduce to the radii of curvature shown in Figure IV.

a socket member b which in turn is carried on a strut assembly foot I9b. In this example, as illustrated in Figure VIII, each end of the strut is a portion of a spherical surface while the cooperating surfaces of the top plate 23b and the strut bearing 2| b are flat. The condition for neutral equilibrium in this example occurs when the sum of the radius or curvature R5 of the upper end of the strut 22?) plus the radius of curvature R6 of the bottom end of the strut is equal to the length L2 of the strut 22b. This example may be derived from the second example by allowing R3 and R4 to each become infinite in length.

This example clearly indicates the condition of neutral equilibrium because as long as the flat surfaces of the strut bearing 2lb and the top plate 23b are horizontal a line passed through the points of contact between the strut and cooperating surfaces is perpendicular to the surfaces and passes through the center of curvature of each end of the strut. Therefore the strut is n. effect a pair of' hemi'spheres' having a common polar ax s and therefore Ina'lli ofthe examples the radii ofthe cooperat mg: surfaces at made" as? small fa Jory life of the bottom endof the strut are as possible consistent with satis- V limit and-a pe'rma This has the effect of to construct a capsule that is both accurate and sufiici'ently' rugged to withstandthe increased lateral forces.

It'therefore'follows; since the radius of curvature or the radii of curvature of the surfaces of the bottom end of the strut are fixed by" strength of the mat making them as small as possible, that the radius or radii of curvature of the surface or surfaces at the top of the strut are varied to's'ecurea-condition of neutral or slightly stable equilibrium.

Referring to Figure XI the upper end of the socket member 290 has a pair of flats 2 8 so that the socket member 206 may be rotated to screw it in or out of the strut assembly foot 1-90 and thus regulate or adjust the heighth of the load receiver with respect to the edges of the pit or with respect to the capsules themselves. This it possible" to accurately thus relieve the" lead re c'eiv'er from twisting strainsthat might cause war ing. g 7

Figure XII SHOWS the elastic or resilient member' 21' which performs two functions in the-improved strut assembly. First, it provides a constant amount of restoring force to resist lateral movement of the load receiver and, second, it and gritty material from the cooperating surfaces at the upper end of at the bottom of the strut are protected against dirt and water by filling the lower socket around the lower end of the strut with a heavy grease. This grease does not restrict the rolling motion of the strut on the bearing but does prevent any dust or dirt that works in below the skirt of the collar 24 from settling into and binding in the close clearance between the lower end of the strut and the cylindrical hole in the socket 20.

This construction porting system and point of force application of force to the capsule located very near the center of the efiective area of the capsule so that the tipping forces are reduced to a minimum. This permits the stabilizing frame work comprising the arms l2 and pipe [8 to be made of relatively light material and still provide sufficient rigidity to hold the capsule pressure plate I in parallel relation to the capsule base 4.

Various modifications of the invention may be made of specific details without departing from the spirit and scope of the invention.

I claim:

l. A support for carrying a load receiver on a hydraulic capsule, comprising, a member supported on the capsule, the member having an upwardly opening socket, a bearing surface in the bottom of the socket, a strut having its lower end supported on the bearing surface in the bottom of the socket said structure extending upwardly from said member, and a bearing plate attached to the load receiver and supported on the strut, said bearing plate having a surface..to engage the upper end of the strut and the strut having an upper end cooperating with the bearing plate, at least one of the cooperating surfaces being convexly curved with a radius of curvature substantially greater than half the length of the strut to permit rolling movement, and at least one of the juxtaposed surfaces of the bearing in the socket and the end of the strut therein being convexly curved with a radius of curvature substantially less than half the length of the strut to permit rolling movement of the strut in the socket.

2. A support for carrying a load receiver on a hydrauliccapsule, comprising, a member supported on the capsule, said member having an upwardly opening flaring socket, a bearing surface forming the bottom of the socket, a strut the lower end of whichis guided in the socket and rests on the bearing surface, a bearing plate attached to the load receiver and having a flat surface engaged by and supported on the upper end of the strut, the upper end of the strut having a spherical surface the center of curvature of which is located between the center and the lower end of the strut, the surface of the lower end of the strut and the bearing surface in the socket being in rolling contact of the surfaces being of convex generally spherical form and having a radius of curvature that is less than half the length of the strut.

3. A support according to claim 2 in which the sum of the radii of curvature of the generally spherical surfaces is substantially equal to the length of the strut, whereby the system when with at least one lightly loaded is theoretically in neutral equilibrium.

4. A support for carrying a load receiver on a hydraulic capsule, comprising a member supported on the capsule, said member having a socket, a bearing surface in the socket, a strut that fits into the socket with its lower end surface resting on the bearing surface, one of the surfaces being convexly curved to permit rolling motion of the strut, a bearing plate attached to the load receiver and having a flat bearing surface resting on the upper end of the strut, the upper end of the strut having a generally spherical form, the center of curvature of which is located between the center and lower end of the strut.

5. In a device of the class described, in combination, a hydraulic capsule structure having formed thereon an upwardly facing bearing surface, a strut having formed thereon a downwardly facing bearing surface at its lower end, which downwardly facing bearing surface engages the upwardly facing bearing surface of the capsule structure, one of said bearing surfaces being convexly curved with a radius of curvature substantially less than half the length of the strut to permit rolling motion between said bearing surfaces, the upper end of said strut having formed thereon an upwardly facing bearing surface, a load receiver structure having formed thereon a downwardly facing bearing surface which downwardly facing bearing surface engages the upwardly facing bearing surface of said strut, at least one of the contacting surfaces at the upper end of the strut being convexly curved with a radius substantially greater than half the length of the strut to permit rolling motion therebetween, and means for preventing substantial shifting of the bearing surfaces formed on said strut in respect to the bearing surfaces formed on said capsule structure and said load receiver structure.

LAWRENCE S. WILLIAMS.

References Cited in the file of this patent UNITED STATES PATENTS 

